Treatment of fibers or fibrous materials containing keratin



Patented Oct. 29, 1946 TREATMENT OF FIBERS OR FIBROUS MATERIALS CONTAINING KERATIN John Bamber Speakman, Far Headingley, Leeds, England, asslgnor to Perm Ltd., Dover, Del.

No Drawing. Application January 25, 1944, Se-

il'i lsNo. 519,665. 'In Great Britain April 23,

Claims.

This invention relates to improvements in the treatment of substances containing keratin, such as hair and wool, and is particularly concerned with treatments for the application of a permanent set'to such substances or for the removal of stress therefrom.

The application is a continuation-in-part of my application Serial No. 210,074, filed May 25, 1938 (Patent No. 2,351,718, issued June 20, 1944) which is a continuation-in-part of my Patent No. 2,201,929, filed December 9, 1935.

Keratin-containing fibers are customarily subjected to steaming or hot water treatment in the.

presence of compounds which may include reducing agents at or only slightly below the boiling point for the release of strain and the application of a permanent set.

It has been proposed to treat wool or hair with a boiling bisulphite solution while tensioning the wool or hair. Such treatment at the boiling point will result in disruption of the disulphide bonds of keratin and the immediate formation of SNH bonds as indicated by the following equations:

where R-SSR and RNH2 represent the peptide and associated side chains of keratin. The reactions take place with great readiness that a suflicient number of linkages to impart a permanent set to the fibers is formed in so short a time that the process is commercially useful. Bisulphite solutions, however, have the disadvantage that at the boiling point of water they are capable of serious destructive attack on hair and at lower temperatures the rate of formation of linkages as represented by Equation 2 above, is negligibly small and therefore proceeds far too slowly to be commercially useful.

The object of the present invention is to provide a treatment whereby release of strain and permanent set are obtained at temperatures appreciably below the boiling point of water.

The invention is based on the observation that salt linkages between the peptide chains of keratin-containing fibers are most stable at pH 6 and thus relaxation in strained fibers is delayed and disulphide bonds remain in a state of strain for a longer time, in which state the bonds are more readily reduced.

Accordingly the invention consists in treating fibrous substance containing keratin, such as wool 2 it is desired to render permanent, with an acid sulphite solution at or about pH 6 at a temperature of from 50" -70 C. whereby the disulphide or cystine bond of keratin is disrupted and further linkages represented by RSNH--R are formed simultaneously in or between the fiber molecules.

Since the hair will reduce the pH of a solution left in contact with it, it is necessary where small quantities of the sulphite solution or composition only are employed to have the pH somewhat higher than 6, for example, up to about 8, so that when the solution or composition is left n contact with the hair the pH will fall to about 6. If the solution or composition is circulated about the hair, pH 6 should be employed.

In the case of the R-S-NHR linkage formed when the fibrous substance is treated accordingto the invention with an acid sulphite solution at approximately pH 6 and a temperature of 50 to C., it has been pointed out above that at temperatures below the boiling point of water the rate of formation of SNH linkages by bisulphite solutions is too slow to be commercially useful; the present invention by critical adjustment of pH as specified enables disruption of the constituent cystine bonds of keratin, followed by the spontaneous formation of SNH linkages to be obtained at the temperatures of from 50-70 C. at a rate which renders the process of commercial utility.

The disruption of the disulphide bond by reduction according to the invention may be employed to relieve stress in the fibers, which stress may have been caused, for example, by deforming the fibers in giving them a desired configuration, and leaves them in such a state that formation of further bonds may take place whereby the fibers will retain permanently any set or configuration which may have been given them.

The salt linkages between the peptide chains of the fibers are most stable at pH 6, relaxation in strained fiber is delayed and disulphide bonds remain in a state of strain for a longer time. As sulphites attack the strained disulphide bonds more readily than the unrestrained bonds the disruption of the bonds is more efflcient at pH 6.

The following are examples of convenient ways of carrying the invention into effect as applied by way of example to the permanent waving of hair.

Example I The hair after the usual preliminary shampoo may be treated with a half molar solution of sodium metabisulphite and sulphite in water containing 5 per cent. by volume of alcohol,the

relative proportions of sulphite and metabisulphite being such as to give a pH of 6.

The solution is circulated about the hair wound on a curler for about 15 minutes, being maintained at a temperature of from 50-70 C. As indicated above the solution is at a pH which brings about the disruption of the disulphide bonds of the hair in an eilicient manner.

If it is not desired to circulate solution about the hair but merely moisten the hair before, or after being wound on a curler, as by applying a, moistened wad of absorbent material to the hair, a solution at a somewhat higher pH, for example about pH 8, is desirably employed since the small amount of solution in contact with the hair decreases in alkalinity due to reaction with the hair. A solution at pH 8 may be made by adding a metabisulphite or suitable acid agent to a 12 per cent. sodium sulphite solution until the desired pH value is attained. The solution may be applied to the hair after a preliminary shampoo and maintained in contact with it at a temperature as indicated above for about 15 minutes. As the pH drops to pH6 on contact with the hair, treatment is in effect carried out with a solution at pH 6.

The treated hair may be raised to the desired temperature by any suitable means for example by placing the head under a hood or other type of hair dryer and subjecting it to the action of the heated air, in the case where circulation of solution is not employed. In the latter arrangement where a stream of heated air is employed, evaporation of water from the hair must be avoided, as by surrounding each curler with a water impermeable sleeve, by covering the head with a water impermeable cap or other convenient means.

The permanent set in this case is realised by the formation of --SNH-bonds as indicated in the following scheme:

The ordinary permanent waving processes operated at or about 100 C. in the presence of assistants such as alkalies or sulphites, are believed to produce the same kind of linkages.

While a permanent wave is obtained by the above treatment without the assistance of an agent for removing or combining with the reducing agent, it is preferred to treat the hair subsequently with a solution of an oxidising agent such as a 10 volume hydrogen peroxide solution or 10 per cent alkali metal persulphate so as to assist in removing any reducing agent remaining in the hair. The usual subsequent procedure of permanent waving may then follow.

Example II In this case, a solution of a reducing agent as specified in Example I is employed, but instead of winding the hair on curlers it is formed into waves or curls on the head after being moistened with the solution. To facilitate manipulation of the hair, a thickening agent may be added to the solution of reducing agent, for instance agar-agar or kieselguhr in suflicient amount to give the consistency of a paste. Suitable wetting agents may also be added.

The formation of further bonds to give permanence to the waves or curls is then brought about by raising the temperature of the hair and contacting solution to about 50 C. as by a stream of hot air, the hair being covered with a water impermeable cap.

The hair may then be given the usual finishing treatment of permanent waving operations.

An alternative manner of carrying out the treatment of the invention according to this example, is to form the hair into waves or curls on the head and treat it with the reducing agent, the subsequent procedure being as set out above.

The combing of the hair may be facilitated if desired by the use of a water soluble lubricant on the hair, for example sulphonated castor oil.

The reagents may be applied by spraying or any other suitable means.

I claim:

1. Method of imparting a permanent set to hair, which comprises treating the hair with a sulphite solution at about pH6 and a temperature of from 50 to C. while maintaining the hair in the form which it is desired to render permanen 2. Method of applying a permanent set to hair comprising treating the hair at a temperature of 50 to 70 0., while it is maintained in a curled or waved condition, at a pH from about 6 to 8 with a sulphite solution in relatively small quantities such that when in contact with the hair the pH of the solution is about pH6.

3. Method as claimed in claim 1 wherein the hair is subsequently treated with a solution of an oxidising agent.

4. Method as claimed in claim 2 wherein the hair is wetted with the sulphite solution is then formed into waves or curls on the head after which the temperature is raised to 50-70 C.

5. Method as claimed in claim 2 wherein the sulphite solution contains a thickening agent.

JOHN BAMBER SPEAKMAN. 

